Respiratory mask assemblies such as the Mirage® nasal mask assembly manufactured by RedMed Ltd. and used for treatment of SDB such as Obstructive Sleep Apnea (OSA) are typically held in position on a patient's head by a headgear assembly. A headgear assembly typically includes a pair of side portions and a rear portion. The side portions are adapted to engage with the patient's mask and the rear portion is adapted to engage the back of the patient's head.
Headgear assemblies are structured to position and stabilize a patient interface, such as a nasal mask, on a patient's face so that a good seal can be maintained. In addition, the headgear assembly should be comfortable so that a patient can wear the mask assembly at night while they sleep. Many prior art headgear assemblies are uncomfortable to wear for long periods. It is desirable that one form of headgear assembly is suitable for a broad range of patients in order to reduce inventory, and ultimately reduce costs.
Completely rigid headgear assemblies are known, but they typically suffer from being uncomfortable to wear for long periods. In addition, because of their rigidity, they typically do not fit a broad range of patients, being suitable only for a subset.
For reasons of costs, it is desirable to be able to cut headgear assemblies from a flat piece of fabric or composite, yet in use the headgear assembly should conform to a complex three-dimensional shape. Hence a problem to overcome is to have a design of headgear assembly which can be easily manufactured by cutting or stamping, and yet in use be able to fit a wide range of head shapes and sizes.
Known forms of headgear assemblies include the ResCap™, ResCap™ II and MIRAGE® headgear, as shown in FIGS. 11-16. These headgear assemblies are constructed from fabric or composite layers of fabric and neoprene. Because of the soft flexible nature of the straps in the headgear assembly, there is the possibility of some movement of the headgear assembly on the patient's head, particularly during the course of a night's sleep. Hence, while the headgear assembly may be initially correctly positioned on a patient's head, they may subsequently move to an incorrect position.
A form of connector to enable the headgear assembly to engage with the patient's mask is taught in U.S. Pat. No. 6,374,826 (Gunaratnam et al.), the contents of which are hereby incorporated by reference.
U.S. Pat. No. 6,422,238 (Lithgow) shows a form of headgear assembly including a quick-release mechanism. The contents of the Lithgow patent are hereby incorporated by reference. The headgear assembly taught by Lithgow includes an upper and lower strap in each side portion extending between the patient's face and the rear of the patient's head. The upper straps lie above the ears on the patient's head. The lower straps lie below the ears on the patient's head.
A problem which can occur with prior art mask assemblies, such as the mask assemblies shown in FIGS. 11-16 and taught by Gunaratnam and Lithgow, is that the lower straps of the mask assemblies can ride up the patient's head while in use and cause chafing and irritation of the lower portion of the patient's ears.